Here’s a familiar riddle to test your thinking: “What can run all day but never gets tired?” Most of us immediately picture a runner, a child full of energy or an animal that never stops moving. But this question doesn’t mean running in quite the usual sense.
Think of the different meanings of ‘run’
People can run along a road, but water can also run through a stream. A machine might run continuously, and a business can run for generations. The key to solving this riddle is to consider meanings beyond a person moving on foot.
What is the answer?
Answer: A river. A river runs or flows day and night. It doesn’t have muscles that become tired, and it doesn’t need a rest the way a person or animal does.
Rivers move because of gravity and the flow of water through a landscape. Their speed may change with rainfall, snowmelt, seasons or the shape of the riverbed, but they don’t experience physical fatigue.
Why this riddle catches people out
The question uses “run” and “tired” together, encouraging you to think of a living creature. The answer becomes obvious once you separate the idea of flowing water from the idea of running with legs.
Other clever answers may work in different versions of the riddle, but “a river” is the traditional solution to this one.
Final answer: A river. Were you thinking of something alive, or did you figure out that the word “run” had a second meaning?


